Ejector

ABSTRACT

In an ejector, a refrigerant passage of a nozzle for decompressing and expanding refrigerant includes a throat portion in which a refrigerant passage sectional area is most reduced, a first taper portion arranged downstream of the throat portion to gradually enlarge the refrigerant passage sectional area, a second taper portion arranged downstream of the first taper portion to gradually enlarge the refrigerant passage sectional area, and an end taper portion arranged in a range from an outlet side of the second taper portion to a refrigerant jet port to gradually enlarge the refrigerant passage sectional area. Furthermore, a second expanding angle at the outlet side of the second taper portion is larger than the first expanding angle at the outlet side of the first taper portion, and an end expanding angle at the outlet side of the end taper portion is smaller than the second expanding angle.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2009-208948filed on Sep. 10, 2009, the contents of which are incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an ejector in which a fluid is drawn bya high-velocity jet fluid jetted from a nozzle. The ejector is suitablyused for an ejector-type refrigerant cycle device.

BACKGROUND OF THE INVENTION

Conventionally, an ejector is known, in which a fluid is drawn from afluid suction port by a suction action of a jet fluid jetted from anozzle for decompressing and expanding the fluid to be jetted. In thiskind of ejector, the velocity energy of the mixture between the jetfluid and the suction fluid drawn from the fluid suction port isconverted to the pressure energy in a pressure increasing portion (e.g.,diffuser portion), so that the pressure of the fluid flowing out of theejector is increased more than the pressure of the suction fluid.

In order to sufficiently increase the pressure of the fluid in thepressure increasing portion of the ejector, it is prefer to increase theflow velocity of the jet fluid, thereby to effectively increase the flowvelocity of the mixed fluid in the ejector. Thus, in a conventionalejector, there is provided with a technical means for improving anenergy conversion efficiency (hereinafter, referred to as “nozzleefficiency ηnoz”) when the pressure energy of a fluid is converted to avelocity energy of the fluid in a nozzle.

For example, Patent Document 1 (JP 11-37577A) describes regarding anejector in which first and second throat portions (throttle portions)for reducing fluid passage sectional areas are provided in a fluidpassage of a nozzle.

In the ejector of Patent Document 1, an expanding angle of a fluidpassage downstream of the second throat portion is reduced near thefluid jet port, so as to restrict a generation of gas and liquidseparation and a generation of a scroll flow in the fluid passagedownstream of the second throat portion, thereby improving the nozzleefficiency ηnoz.

The nozzle efficiency ηnoz is specifically defined by the followingformula F1.ηnoz=(Vnoz²/2)/Δinoz  (F1)

Here, the Vnoz is the velocity of the jet fluid, and Δinoz is a decreaseamount of a special enthalpy when a fluid of per weight unit isdecompressed and expanded in iso-entropy in the nozzle. That is, theΔinoz is a difference of the special enthalpy between the enthalpy ofthe fluid at the inlet of the nozzle and the enthalpy of the fluid atthe outlet of the nozzle.

In the ejector of the Patent Document 1, it is the pre-condition inwhich the fluid flowing into the first throat of the nozzle is in aliquid state. However, in the ejector of the Patent Document 1, if agas-liquid two-phase fluid flows into the first throat of the nozzle, itis difficult to improve the nozzle efficiency. ηnoz.

The reasons will be described with reference to FIGS. 13A and 13B. FIG.13A is a Mollier diagram for explaining a decompression stage of aliquid fluid decompression in the nozzle of the ejector, and FIG. 13B isa Mollier diagram for explaining a decompression stage of a gas-liquidfluid decompression in the nozzle of the ejector. In addition, in FIGS.13A and 13B, the dashed lines show the isoentropic curved line.

The Δinoz in the above formula F1 is a value determined by thephysicality of the fluid. Thus, in order to improve the nozzleefficiency ηnoz, it is necessary to increase the Vnoz by decreasing theloss while the fluid is decompressed in the nozzle. Therefore, it isdesirable for the fluid to be decompressed in the nozzle along theisoentropic curved line.

Furthermore, as shown in FIGS. 13A, 13B, the isoentropic curved line isan approximately S-shaped curved line, in which a decrease degree of theenthalpy becomes gradually smaller as the pressure decreases when theliquid fluid is decompressed to become in a gas-liquid two-phase state,and the decrease degree of the enthalpy becomes gradually larger as thepressure decreases when the gas-liquid two-phase fluid having arelatively small pressure is further decompressed.

In the ejector of Patent Document 1, when the liquid fluid flows intothe nozzle (i.e., the first throat), the fluid is decompressedapproximately along the isoentropic curved line in the entiredecompression as shown in FIG. 13A even when the expanding angle of thefluid passage downstream of the second throat is made small near thefluid jet port.

In contrast, in a case where gas-liquid two-phase fluid having arelatively low pressure flows into the nozzle, it is difficult toperform a decompression stage approximately along the isoentropic curvedline, as shown in FIG. 13B. As a result, when the fluid flowing into thefirst throat portion of the nozzle of Patent Document 1 is in thegas-liquid two-phase state, it is difficult to improve the nozzleefficiency ηnoz.

SUMMARY OF THE INVENTION

The inventors of the present application proposes an ejector that canprovide a high nozzle efficiency ηnoz even when gas-liquid two-phasefluid flows into a nozzle, as in JP. 2009-221883A (hereinafter, referredto as “prior application example”). The nozzle of the ejector of theprior application example includes a single throat portion, and anexpanding angle of a fluid passage downstream of the throat portion isenlarged near the fluid jet port of the nozzle.

Thus, the passage sectional area of the fluid passage downstream of thethroat portion of the nozzle can be changed (enlarged) such that thedecompression of the fluid is performed along the isoentropic curvedline when gas-liquid two-phase fluid flows into the nozzle. That is, thepassage area of the nozzle can be enlarged to correspond to the volumeexpansion, even when the fluid volume is expanded by the increase of thegas ratio when the gas-liquid two-phase fluid is decompressed andexpanded. Thus, the decompression stage of the fluid can be approachedto the isoentropic curved line.

In the ejector of the prior application example, the nozzle efficiencyηnoz can be improved when gas-liquid two-phase fluid flows into thenozzle. However, in this case, it may be difficult to sufficiently drawthe fluid from the fluid suction port, and thereby the energy conversionefficiency (i.e., ejector efficiency ηe) cannot be improved in theentire ejector.

The ejector efficiency ηe can be defined by the following formula F2.ηe=(1+Ge/Gnoz)×(ΔP/ρ)/Δi  (F2)

Here, Ge is the flow amount of the suction fluid, Gnoz is the flowamount of the jet fluid, ΔP is the pressure increase amount in thediffuser portion, ρ is the density of the suction fluid, and Δi is theenthalpy difference between the nozzle inlet and the nozzle outlet.

According to the studies by the inventors of the present applicant, ifthe expanding angle of the fluid passage is enlarged near the fluid jetport as in the previous application example, the fluid may be injectedto be expanded unnecessary in a radial direction of the nozzle.Furthermore, if the jet fluid is unnecessary expanded in the radialdirection of the nozzle, the suction fluid drawn from the fluid suctionport may be interrupted by the expanded jet fluid.

If the suction fluid flowing into the ejector is interrupted, the flowamount of the suction fluid is decreased, thereby decreasing the ejectorefficiency ηe, as being easily known from the above formula F2.

In view the above problems, it is an object of the present invention toprovide an ejector which can prevent a decrease of the ejectorefficiency ηe even when a fluid with a gas-liquid two-phase state flowsinto a nozzle in the ejector.

To achieve the above object, an ejector according to a first example ofthe present invention includes: a nozzle configured to decompress andexpand a fluid and to jet the fluid from a fluid jet port; and a bodyprovided with a fluid suction port from which a fluid is drawn by ahigh-speed jet fluid jetted from the fluid jet port, and a pressureincreasing portion in which a velocity energy of a mixture fluid betweenthe jet fluid and a suction fluid drawn from the fluid suction port isconverted to a pressure energy thereof. Furthermore, an inner peripheralsurface of the nozzle defining a fluid passage includes a throat portionin which a fluid passage sectional area of the fluid passage is mostreduced, a first taper portion arranged downstream of the throat portionto gradually enlarge the fluid passage sectional area as toward a flowdirection of the jet fluid, a second taper portion arranged downstreamof the first taper portion to gradually enlarge the fluid passagesectional area as toward the flow direction of the jet fluid, and an endtaper portion arranged in a range from an outlet side of the secondtaper portion to the fluid jet port to gradually enlarge the fluidpassage sectional area as toward the flow direction of the jet fluid. Inthe ejector, when an axial cross section including an axial line of thenozzle is defined as a standard cross section, a second expanding angleat an outlet side of the second taper portion on the standard crosssection is larger than a first expanding angle at an outlet side of thefirst taper portion on the standard cross section, and an end expandingangle at an outlet side of the end taper portion on the standard crosssection is smaller than the second expanding angle.

Thus, the second expanding angle can be made larger than the firstexpanding angle, and thereby an increase degree of the fluid passagesectional area in the second taper portion becomes larger than anincrease degree of the fluid passage sectional area in the first taperportion.

Therefore, in a case where gas-liquid two-phase fluid flowing into thenozzle is decompressed and expanded while passing through the throatportion, the first taper portion and the second taper portion in thisorder, the fluid passage area of the nozzle can be enlarged tocorrespond to the volume expansion, even when the fluid volume isexpanded by the increase of the gas ratio.

In this case, it is possible to effectively reduce the loss due to thepassage resistance when the fluid passes through the first taper portionand the second taper portion in this order. Thus, the decompressionstage of the fluid in the nozzle can be approached to the decompressionstate along the isoentropic curved line, thereby improving the nozzleefficiency.

Furthermore, because the end expanding angle at the outlet side of theend taper portion is made smaller than the second expanding angle, itcan restrict the jet fluid from the fluid jet port from beingunnecessary expanded in a radial direction that is perpendicular to theaxial line of the nozzle. Accordingly, the suction fluid can easily flowinto the interior of the ejector, and it can prevent the flow amount ofthe suction fluid from being decreased, thereby preventing a decrease ofthe ejector efficiency.

As a result, even when the fluid with a gas-liquid two-phase state flowsinto the nozzle, it can prevent the nozzle efficiency and the ejectorefficiency ηe from being reduced in the ejector.

For example, the second taper portion may be formed into a curved lineshape with a slight convex at the fluid passage side, on the standardcross section. Thus, even when the increase degree of the fluid passagesectional area of the second taper portion is smoothly changed, thedecompression stage of the fluid in the nozzle can be more approached tothe decompression stage of the isoentropic curved line.

Alternatively, the second taper portion may be formed into a straightline shape on the standard cross section. In this case, the second taperportion can be easily produced to reduce the product cost, while thedecompression stage of the fluid in the nozzle can be further approachedto the decompression, stage of the isoentropic curved line.

Furthermore, the inner peripheral surface of the nozzle defining thefluid passage may further include an introduction taper portion arrangedin a range from the throat portion to, the first taper portion, togradually enlarge the fluid passage sectional area as toward the flowdirection of the jet fluid, and an introduction expanding angle at anoutlet side of the introduction taper portion on the standard crosssection may be larger than the first expanding angle.

When gas-liquid two-phase fluid flowing into the nozzle is decompressedand expanded while passing through the throat portion, the first taperportion and the second taper portion in this order, the gas ratio israpidly increased at a position immediately after passing through thethroat portion in the nozzle.

Because the introduction taper portion is provided such that theintroduction expanding angle is made larger than the first expandingangle, the fluid passage sectional area can be enlarged to correspond tothe rapid volume expansion due to a rapid increase of the gas ratio,thereby further effectively improving the nozzle efficiency.

For example, the introduction taper portion may be formed into a curvedline with a convex at the radial outer side of the fluid passage of thenozzle, on the standard cross section. Thus, the increase degree of thefluid passage sectional area of the introduction taper portion can besmoothly changed, and thereby the decompression stage of the fluid inthe nozzle can be more approached to the decompression stage of theisoentropic curved line.

Alternatively, the introduction taper portion may be formed into astraight line shape on the standard cross section. In this case, theintroduction taper portion can be easily produced to reduce the productcost, while the decompression stage of the fluid in the nozzle can befurther approached to the decompression stage of the isoentropic curvedline.

Furthermore, the second expanding angle may be made equal to or largerthan 1.33 times of the first expanding angle. In this case, it canfurther stably improve of the nozzle efficiency ηnoz.

According to a second example of the present invention, an ejectorincludes: a nozzle configured to decompress and expand a fluid and tojet the fluid from a fluid jet port; a body provided with a fluidsuction port from which a fluid is drawn by a high-speed jet fluidjetted from the fluid jet port, and a pressure increasing portion inwhich a velocity energy of a mixture fluid between the jet fluid and asuction fluid drawn from the fluid suction port is converted to apressure energy thereof. Furthermore, an inner peripheral surface of thenozzle defining a fluid passage includes a throat portion in which afluid passage sectional area of the fluid passage is most reduced, afirst taper portion arranged downstream of the throat portion togradually enlarge the fluid passage sectional area as toward a flowdirection of the jet fluid, a second taper portion arranged downstreamof the first taper portion to gradually enlarge the fluid passagesectional area as toward the flow direction of the jet fluid, and an endtaper portion arranged in a range from an outlet side of the secondtaper portion to the fluid jet port to gradually enlarge the fluidpassage sectional area as toward the flow direction of the jet fluid. Inaddition, an increase degree of the fluid passage sectional area in thesecond taper portion is larger than an increase degree of the fluidpassage sectional area in the first taper portion. When an axial crosssection including an axial line of the nozzle is defined as a standardcross section, an end expanding angle at an outlet side of the end taperportion on the standard cross section is smaller than an outletexpanding angle at an outlet side of the taper portion on the standardcross section.

Thus, the increase degree of the fluid passage sectional area in thesecond taper portion becomes larger than the increase degree of thefluid passage sectional area in the first taper portion, therebyimproving the nozzle efficiency. Furthermore, because the end expandingangle at the outlet side of the end taper portion is made smaller thanthe second expanding angle, it can restrict the ejector efficiency frombeing decreased.

As a result, even when the fluid with a gas-liquid two-phase state flowsinto the nozzle, it can prevent the nozzle efficiency and the ejectorefficiency from being reduced.

According to a third example of the present invention, an ejectorincludes: a nozzle configured to decompress and expand a fluid and tojet the fluid from a fluid jet port; a needle disposed inside of thefluid passage of the nozzle to extend a fluid flow direction; and a bodyprovided with a fluid suction port from which a fluid is drawn by ahigh-speed jet fluid jetted from the fluid jet port, and a pressureincreasing portion in which a velocity energy of a mixture fluid betweenthe jet fluid and a suction fluid drawn from the fluid suction port isconverted to a pressure energy thereof. Furthermore, an inner peripheralsurface of the nozzle defining a fluid passage includes a throat portionin which a fluid passage sectional area of the fluid passage is mostreduced, an inner peripheral surface of the nozzle defining the fluidpassage includes a throat portion in which a fluid passage sectionalarea of the fluid passage, is most reduced, a taper portion arrangeddownstream of the throat portion to gradually enlarge the fluid passagesectional area as toward a flow direction of the jet fluid, and an endtaper portion arranged in a range from a downstream side of the taperportion to the fluid jet port to gradually enlarge the fluid passagesectional area as toward the flow direction of the jet fluid. The fluidpassage, defined between an outer peripheral surface of the needle andthe taper portion, includes a first expanding passage portion in whichthe fluid passage sectional area is gradually enlarged toward a flowdirection of the jet fluid, and a second expanding passage portionarranged downstream of the first expanding passage portion to graduallyenlarge the fluid passage sectional area toward the flow direction ofthe jet fluid. In addition, an increase degree of the fluid passagesectional area in the second expanding passage portion is larger than anincrease degree of the fluid passage sectional area in the firstexpanding passage portion. When an axial cross section including anaxial line of the nozzle is defined as a standard cross section, an endexpanding angle at an outlet side of the end taper portion on thestandard cross section is smaller than an outlet expanding angle at anoutlet side of the taper portion on the standard cross section.

Thus, the increase degree of the fluid passage sectional area in thesecond expanding passage portion is larger than the increase degree ofthe fluid passage sectional area in the first expanding passage portion.Therefore, even when gas-liquid two-phase fluid flowing into the nozzleis decompressed and expanded while passing through the throat portionand the taper portion in this order, the passage area of the nozzle canbe enlarged to correspond to an increase of the gas ratio. Accordingly,it can further improve the nozzle efficiency ηnoz.

Furthermore, because the end expanding angle is made smaller than thesecond expanding angle, it can restrict a decrease of the ejectorefficiency. As a result, even when the fluid with a gas-liquid two-phasestate flows into the nozzle, it can prevent the nozzle efficiency andthe ejector efficiency ηe from being reduced in the ejector.

For example, first and second passage expanding portions may be formedin a fluid passage between the inner peripheral surface of the taperportion of the nozzle and the outer peripheral surface of the needle. Inthis case, an increase degree of the fluid passage sectional area in thesecond expanding passage portion may be larger than an increase degreeof the fluid passage sectional area in the first expanding passageportion, and the taper portion may be configured by a first taperportion provided downstream of the throat portion, and a second taperportion provided downstream of the first taper portion. Furthermore, asecond expanding angle at an outlet side of the second taper portion onthe standard cross section may be larger than a first expanding angle atan outlet side of the first taper portion on the standard cross section,and an outer peripheral surface of the needle, positioned radiallyinside of the taper portion, may be formed into a straight line shape onthe standard cross section.

Alternatively, the taper portion may be formed into a straight lineshape on the standard cross section. Furthermore, the needle, positionedradially inside of the taper portion, may include a first reductionportion in which the sectional area is gradually reduced toward a flowdirection of the jet fluid, and a second reduction portion arrangeddownstream of the first reduction portion to gradually reduce thesectional area toward the flow direction of the jet fluid. In this case,a reduction degree of the sectional area of the first reduction portionmay be smaller than a reduction degree of the sectional area of thesecond reduction portion.

Alternatively, the taper portion may be configured by a first taperportion provided downstream of the throat portion, and a second taperportion provided downstream of the first taper portion. Furthermore, theneedle, positioned radially, inside of the first taper portion definingthe first expanding passage portion, may include a first reductionportion in which the sectional area is gradually reduced toward a flowdirection of the jet fluid. In this case, the needle, positionedradially inside of the second taper portion defining the secondexpanding passage portion, may include a second reduction portion inwhich the sectional area is gradually reduced toward a flow direction ofthe jet fluid.

Furthermore, the inner peripheral surface of the nozzle may furtherinclude an introduction taper portion arranged in a range from thethroat portion to the taper portion, to gradually enlarge the fluidpassage sectional area as toward the flow direction of the jet fluid. Inthis case, an introduction expanding angle at an outlet side of theintroduction taper portion on the standard cross section is larger thanthe first expanding angle.

In this case, the fluid passage sectional area can be enlarged tocorrespond to the rapid volume expansion due to a rapid increase of thegas ratio immediately after passing through the throat portion, therebyfurther effectively improving the nozzle efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and advantages of the present invention will be morereadily apparent from the following detailed description of preferredembodiments when taken together with the accompanying drawings. Inwhich:

FIG. 1 is an entire schematic diagram of an ejector-type refrigerantcycle device according to a first embodiment of the invention;

FIG. 2 is an axial sectional view showing an ejector according to thefirst embodiment;

FIG. 3 is an enlarged sectional view showing a nozzle according to thefirst embodiment;

FIG. 4 is a graph showing the relationship between a second expandingangle θ2 and a nozzle efficiency ηnoz;

FIG. 5 is an enlarged sectional view showing a nozzle according to asecond embodiment of the invention;

FIG. 6 is an enlarged sectional view showing a nozzle according to athird embodiment of the invention;

FIG. 7 is an enlarged sectional view showing a nozzle according to afourth embodiment of the invention;

FIG. 8 is an enlarged sectional view showing a nozzle according to afifth embodiment of the invention;

FIG. 9 is an enlarged sectional view showing a nozzle according to asixth embodiment of the invention;

FIG. 10 is an entire schematic diagram showing one example of anejector-type refrigerant cycle device according to the otherembodiments;

FIG. 11 is an entire schematic diagram showing another example of anejector-type refrigerant cycle device according to the otherembodiments;

FIG. 12 is an entire schematic diagram showing another example of anejector-type refrigerant cycle device according to the otherembodiments; and

FIG. 13A is a Mollier diagram showing a decompression stage when aliquid fluid flows into a nozzle, and FIG. 13B is a Mollier diagramshowing a decompression stage when a gas-liquid two-phase fluid flowsinto a nozzle.

EMBODIMENTS

(First Embodiment)

A first embodiment of the invention will be described below withreference to FIGS. 1 to 4. In the present embodiment, an ejector 16 ofthe invention is typically applied to an ejector-type refrigerant cycledevice 10 of an air conditioner for a vehicle.

FIG. 1 is an entire schematic diagram of the ejector-type refrigerantcycle device 10 of the present embodiment. In the ejector-typerefrigerant cycle device 10, the compressor 11 is configured to drawrefrigerant and to compress the drawn refrigerant. The compressor 11 isrotated, and driven by a drive force from an engine (not shown) for avehicle traveling.

As the compressor 11, a variable capacity compressor or a fixeddisplacement compressor may be used. The variable capacity compressor isadapted to adjust a refrigerant discharge capacity by changingrefrigerant discharge amount. Furthermore, the fixed displacementcompressor is adapted to adjust a refrigerant discharge capacity bychanging an operation rate of the compressor using interruption of theelectromagnetic clutch. When an electrical compressor is used as thecompressor 11, the refrigerant discharge capacity of the compressor 11can be adjusted by adjusting the rotational speed of the electricalmotor.

A refrigerant radiator 12 is connected to a refrigerant discharge sideof the compressor 11. The radiator 12 is a heat-radiation heat exchangerin which high-pressure refrigerant discharged from the compressor 11 isheat-exchanged with outside air (i.e., air outside of the vehiclecompartment) blown by a cooling fan 12 a, thereby cooling thehigh-pressure refrigerant. The cooling fan 12 a is an electrical blowerin which the rotational speed (air blowing amount) is controlled by acontrol voltage output from an air conditioning controller (not shown).

In the ejector-type refrigerant cycle device 10 of the presentembodiment, a Freon-based refrigerant may be used. In this case, theejector-type refrigerant cycle device 10 is configured to form asub-critical refrigerant cycle, in which the refrigerant pressure of thehigh-pressure side does not higher than the critical pressure of therefrigerant. Thus, the radiator 12 is adapted as a condenser in whichrefrigerant is condensed. In the present embodiment, the refrigerant isone example of a fluid.

A receiver 12 b is connected to a refrigerant outlet side of theradiator 12. The receiver 12 b is a gas-liquid separator, in which therefrigerant flowing out of the radiator 12 is separated into gasrefrigerant and liquid refrigerant, and the surplus liquid refrigerantis stored in the receiver 12 b. In the present embodiment, the radiatorand the receiver 12 b are configured integrally; however, the radiator12 and the receiver 12 b may be configured separately from each other.

Furthermore, as the radiator 12, a sub-cool type condenser may be usedto include a condensation heat exchanging portion for cooling andcondensing the refrigerant, a receiver portion in which the refrigerantintroduced from the condensation heat exchanging portion is separatedinto gas refrigerant and liquid refrigerant, and a super-cooling heatexchanging portion in which the saturated liquid refrigerant from thereceiver portion is super-cooled.

An expansion valve 13 as a variable throttle mechanism is connected to aliquid refrigerant outlet of the receiver 12 b. The expansion valve 13is adapted as a decompression means for decompressing the high-pressureliquid refrigerant flowing out of the receiver 12 b into a middlepressure refrigerant of a gas-liquid two-phase state, and is alsoadapted as a flow adjusting means for adjusting a flow amount of therefrigerant to flow toward downstream of the expansion valve 13.

In the present embodiment, a thermal expansion valve is used as theexpansion valve 13. Specifically, the thermal expansion valve has atemperature sensing portion 13 a arranged in a refrigerant passage at arefrigerant outlet side of a discharge side evaporator 17 describedlater. The thermal expansion valve 13 is a variable throttle mechanism,in which a super-heat degree of the refrigerant at the refrigerantoutlet side of the discharge side evaporator 17 is detected based ontemperature and pressure of the refrigerant at the refrigerant outletside of the discharge side evaporator 17, and its valve-open degree(refrigerant flow amount) is adjusted by using a mechanical mechanism sothat the super-heat degree of the refrigerant at the refrigerant outletside of the discharge side evaporator 17 is approached to apredetermined value.

A branch portion 14 is connected to a refrigerant outlet side of theexpansion valve 13, to branch the flow of a gas-liquid middle-pressurerefrigerant decompressed and expanded by the expansion valve 13 into twostreams. For example, the branch portion 14 is a three-way jointstructure having three ports that are used as one refrigerant inlet andtwo refrigerant outlets. The branch portion 14 may be configured bybonding plural pipes, or may be configured by providing pluralrefrigerant passages in a metal block member or a resin block member.

One refrigerant branched in the branch portion 14 flows into a nozzleside pipe 15 a that connects one refrigerant outlet of the branchportion 14 and the inlet of the nozzle 161 of the ejector 16 with eachother. The other refrigerant branched in the branch portion 14 flowsinto a suction side pipe 15 b that connects the other refrigerant outletof the branch portion 14 and a refrigerant suction port 162 a of theejector 16 with each other.

The ejector 16 is adapted as a refrigerant decompression means fordecompressing and expanding a high-pressure refrigerant, and as arefrigerant circulation means for circulating the refrigerant by thesuction action of a high-speed refrigerant flow jetted from the nozzle161. A detail structure of the ejector 16 will be described withreference to FIGS. 2 and 3. FIG. 2 is an axial sectional view includingan axial line φ of the nozzle 161 of the ejector 16, and FIG. 3 is anenlarged sectional view showing the nozzle 161 of FIG. 2. The crosssection of the nozzle 161 shown in FIGS. 2 and 3 is the basic sectionthereof.

The ejector 16 of the embodiment is configured to have the nozzle 161and a body 162. First, the nozzle 161 is formed from an approximatelycylindrical member made of a metal (for example, brass, a stainlessalloy). As shown in FIG. 3, the nozzle 161 is formed in a taper shapetapered toward in a refrigerant flow direction. In the interior of thenozzle 161, a refrigerant passage (i.e., fluid passage), through whichthe refrigerant flowing from the nozzle side pipe 15 a flows, is formedalong the axial line φ.

The refrigerant passage of the nozzle 161 is formed and defined by aninner peripheral surface of the nozzle 161. By suitably changing aradial dimension of the refrigerant passage the nozzle 161, therefrigerant passage sectional area (fluid passage sectional area) of therefrigerant passage of the nozzle 161 can be suitably changed. Thus, therefrigerant passage of the nozzle 161 is configured by combining pluralcylindrical spaces arranged on the same axial line, or/and plural cornspaces arranged on the same axial line.

More specifically, the inner peripheral surface of the nozzle 161 isprovided with a refrigerant jet port (fluid jet port) 161 a, a throatportion 161 b and a taper portion 161 c. The refrigerant jet port 161 ais provided at the most downstream portion in the refrigerant passage ofthe nozzle 161, such that the refrigerant is jetted from the refrigerantjet port 161 a. The throat portion 161 b is the most throttled portionin the refrigerant passage sectional area, and is provided in a middleportion of the refrigerant passage of the nozzle 161. The taper portion161 c is provided in the nozzle 161 downstream of the throat portion 161b in the refrigerant flow.

In the present embodiment, the nozzle 161 is configured as in a Lavalnozzle, such that the refrigerant flowing into the nozzle 161 isdecompressed and expanded in iso-entropy thereby accelerating the flowspeed of the refrigerant jetted from the refrigerant jet port 161 a tothe sound speed.

Furthermore, an end taper portion 161 d is provided in the innerperipheral surface of the nozzle 161, in an end portion adjacent to therefrigerant jet port 161 a of the refrigerant passage. That is, the endtaper portion 161 d is provided in a range from an outlet side of thetaper portion 161 c to the refrigerant jet port 161 a such that therefrigerant passage area is gradually increased as toward therefrigerant flow direction.

The taper portion 161 c is divided into first and second taper portions161 e, 161 f. When an expanding angle of an outlet side of the firsttaper portion 161 e on the standard cross section is a first expandingangle θ1, when an expanding angle of an outlet side of the second taperportion 161 f on the standard cross section is a second expanding angleθ2, and when an expanding angle of an outlet side of the end taperportion 161 d on the standard cross section is an end expanding angleθ3, the expanding angles θ1, θ2, θ3 are set to satisfy the followingformulas F3 and F4.θ1<θ2  (F3)θ2>θ3  (F4)

That is, the second expanding angle θ2 is larger than the firstexpanding angle θ1, and the end expanding angle θ3 is smaller than thesecond expanding angle θ2. Specifically, in the present embodiment, thesecond expanding angle θ2 is made equal to or larger than 1.33 of thefirst expanding angle θ1. More specifically, the second expanding angleθ2 is made approximately in a range from 1.4 to 2.0 times of the firstexpanding angle θ1 (i.e., θ2/θ1=1.4-2.0).

That is, an increase degree of the refrigerant passage sectional area ofthe second taper portion 161 f is made larger than an increase degree ofthe refrigerant passage sectional area of the first taper portion 161 e,and an increase degree of the refrigerant passage sectional area of theend taper portion 161 d is made smaller than an increase degree of therefrigerant passage sectional area of the second taper portion 161 f.

The first taper portion 161 e and the second taper portion 161 f aresmoothly connected at a connection portion by chamfering, and the secondtaper portion 161 f and the end taper portion 161 d are smoothlyconnected at a connection portion by chamfering. Thus, it can preventthe refrigerant passage sectional area from being rapidly restricted atthe respective connection portion, thereby reducing the loss of thekinetic energy of the refrigerant.

The first expanding angle θ1 at the outlet side of the first taperportion 161 e is the expanding angle at the most downstream side of thefirst taper portion 161 e except for the chamfering portion. That is,the first expanding angle θ1 is the angle defined by the tangentiallines at the most downstream portion of the first taper portion 161 e onthe standard cross section. The second expanding angle θ2 and the endexpanding angle θ3 are also defined similar to the first expanding angleθ1.

Furthermore, in the present embodiment, the first taper portion 161 eand the end taper portion 161 d are formed into a line shape on thestandard cross section, and the second taper portion 161 f is formedinto a curved line with a convex at the radial inner side of therefrigerant passage on the standard cross section.

The nozzle 161 is received in the interior of the body 162 and is fixedto the body 162 by fitting or the like, thereby preventing therefrigerant from leaking from the fitted portion (fixing portion) of thenozzle 161. If a refrigerant leakage from the fixing portion of thenozzle 161 can be prevented, the nozzle 161 may be bonded and fixed tothe body 162 by using a connection means such as an adhesion, a welding,press-fitting, soldering and the like.

The body 162 is formed from an approximately cylindrical metal (e.g.,aluminum). The body 162 is adapted as a fixing member for supporting andfixing the nozzle 161 therein, and defines an outer shell of the ejector16. The body 162 may be made of a resin, if the above function can beobtained in the body 162. The body 162 is, provided with a refrigerantsuction port (i.e., fluid suction port) 162 a, a suction passage 162 b,a diffuser portion 162 c as the pressure increasing portion; and thelike.

The refrigerant suction port 162 a is a through hole provided topenetrate through the interior and the exterior of the body 162. Therefrigerant suction port 162 a is provided such that the refrigerantflowing out of the suction side evaporator 19 is drawn into the ejector16, by a suction action caused due to a pressure decease of theinjection refrigerant. The refrigerant suction port 162 a is positionedat an outer peripheral side of the nozzle 161, and is made tocommunicate with the refrigerant jet port 161 a via the suction passage162 b.

Thus, an inlet space for introducing the refrigerant therein is formednear the refrigerant suction port 162 a in the body 162, and the suctionpassage 162 b is formed in a space between an outer peripheral surfaceof the tapered end portion of the nozzle 161 and an inner peripheralsurface of the body 162 so as to introduce the suction refrigerantflowing into the interior of the body 162 to the diffuser portion 162 c.

In the present embodiment, the refrigerant passage area of the suctionpassage 162 b is changed to be gradually reduced toward the downstreamof the refrigerant flow, so that the flow speed of the suctionrefrigerant flowing through the suction passage 162 b is increased to beapproached to the flow speed of the jet refrigerant.

The diffuser portion 162 c is configured to mix the jet refrigerantjetted from the nozzle 161 and the suction refrigerant drawn from therefrigerant suction port 162 a, and to convert the kinetic energy ofmixed gas-liquid two-phase refrigerant to the pressure energy.Specifically, the diffuser portion 162 c is formed to have a refrigerantpassage in which the refrigerant passage section area is graduallyenlarged toward the refrigerant flow direction, thereby increasing therefrigerant, pressure by decelerating the refrigerant flow.

Furthermore, the refrigerant passage of the diffuser portion 162 c isshaped, such that the expanding degree of the refrigerant passagesectional area of the diffuser portion 162 c at its inlet side ischanged larger than the expanding degree of the refrigerant passagesectional area of the diffuser portion 162 c at its outlet side. Thatis, at the inlet side of the diffuser portion 162 c, the refrigerantpassage sectional area is rapidly expanded than the average expandingdegree from the inlet to the outlet of the diffuser portion 162 c. Incontrast, at the outlet side of the diffuser portion 162 c, therefrigerant passage sectional area is gradually expanded than theaverage expanding degree from the inlet to the outlet of the diffuserportion 162 c.

On the standard cross section that is the section including the axialline φ, the sectional shape of the inlet side refrigerant passage of thediffuser portion 162 c is formed in a curved line curved in a convextoward the inner peripheral side, and the sectional shape of the outletside refrigerant passage of the diffuser portion 162 c is formed in acurved line curved in a convex toward the outer peripheral side. Thus,it can restrict a separation of the refrigerant in the outlet portion ofthe diffuser portion 162 c, thereby reducing the loss of the energycontained in the refrigerant.

The discharge side evaporator 17 is located downstream of the diffuserportion 162 c of the ejector 162, as, shown in FIG. 1. The dischargeside evaporator 17 is a heat-absorbing heat exchanger, in which therefrigerant flowing out of the diffuser portion 162 c is heat-exchangedwith air blown by a blower fan 17 a, thereby evaporating the refrigerantto have heat absorbing action.

The blower fan 17 a is an electrical blower in which the rotationalspeed (air blowing amount) is controlled by a control voltage outputfrom the air conditioning controller. The refrigerant outlet of thedischarge side evaporator 17 is coupled to a refrigerant suction port ofthe compressor 11.

The suction side pipe 15 b, in which the other refrigerant branched inthe branch portion 14 flows, is connected to the refrigerant suctionport 162 a of the ejector 16 via a throttle mechanism 18 and a suctionside evaporator 19. The throttle mechanism 18 is adapted as adecompression means for decompressing the refrigerant to flow into thesuction side evaporator 19, and is also adapted as a flow adjustingmeans for adjusting a flow amount of the refrigerant to flow into thesuction side evaporator 19. As the throttle mechanism 18, a fixedthrottle such as a capillary tube, an orifice or the like can be used.

The suction side evaporator 19 is configured to perform heat exchangebetween the refrigerant flowing out of the throttle mechanism 18 and airblown by the blower fan 17 a and having passed through the dischargeside evaporator 17, and is adapted as a heat-absorbing heat exchanger inwhich the refrigerant is evaporated so as to exert heat-absorbingaction. The refrigerant outlet of the suction side evaporator 19 iscoupled to the refrigerant suction port 162 a of the ejector 162.

In the present embodiment, both the discharge side evaporator 17 and thesuction side evaporator 19 are integrally assembled to each other. Theair blown by the blower fan 17 a flows as in the arrow 100. Thus, theair blown by the blower fan 15 a is cooled at first in the dischargeside evaporator 17, and is further cooled in the suction side evaporator19, and then flows into a space to be cooled (e.g., vehiclecompartment). Thus, in the present embodiment, the same space to becooled (e.g., vehicle compartment) can be cooled by using both thedischarge side evaporator 17 and the suction side evaporator 19.

Next, operation of the above-described ejector-type refrigerant cycledevice 10 of the present embodiment will be described. When thecompressor 11 is driven by a vehicle engine, high-temperature andhigh-pressure refrigerant discharged from the compressor 11 flows intothe radiator 12. The radiator 12 is configured to cool and condense thehigh-temperature refrigerant by using outside air. The high-pressurerefrigerant flowing out of radiator 12 flows into the receiver 12 b, andis separated into gas refrigerant and liquid refrigerant in the receiver12 b.

The separated liquid refrigerant flowing out of the receiver 12 b flowsinto the expansion valve 13, and is decompressed and expanded in theexpansion valve 13 to a middle pressure of a gas-liquid two-phase state.Thereafter, the decompressed and expanded refrigerant flowing out of theexpansion valve 13 flows into the branch portion 14. At this time, theexpansion valve 13 adjusts the flow amount of the refrigerant flowingtoward downstream so that a super-heating degree of the refrigerant atthe outlet side of the discharge side evaporator 17 is approached to thepredetermined value.

The refrigerant decompressed and expanded by the expansion valve 13flows into the branch portion 14, and is branched by the branch portion14 into a flow of the refrigerant flowing into the nozzle side pipe 15 aand a flow of the refrigerant flowing into the suction side pipe 15 b.At this time, a flow ratio Gnoz/Ge of a refrigerant flow amount Gnozflowing into the nozzle side pipe 15 a to a refrigerant flow amount Geflowing into the suction side pipe 15 b is determined by using flowcharacteristics (pressure loss characteristics) of the nozzle 161 andthe throttle mechanism 18, thereby obtaining a high coefficient ofperformance (COP) in the entire cycle.

The middle pressure refrigerant of gas-liquid two-phase state flowinginto the ejector 16 via the nozzle side pipe 15 a is furtherdecompressed by the nozzle 161. At this time, the pressure energy of therefrigerant is converted to the speed energy of the refrigerant in thenozzle 161, and gas-liquid refrigerant is jetted with a high speed fromthe refrigerant jet port 161 a of the nozzle 161. Thus, the gasrefrigerant evaporated in the suction side evaporator 19 is drawn intothe ejector 16 from the refrigerant suction port 162 a by the high-speedrefrigerant jetted from the refrigerant jet port 161 a.

Furthermore, the jet refrigerant jetted from the nozzle 161 and thesuction refrigerant drawn from the refrigerant suction port 162 a flowinto the diffuser portion 162 c of the ejector 16. In the diffuserportion 162 c, the jet refrigerant and the suction refrigerant aremixed. Furthermore, the passage sectional area is enlarged in thediffuser portion 162 c as toward downstream so that the speed energy ofthe refrigerant is converted to the pressure energy thereof, therebyincreasing the pressure of the refrigerant.

The refrigerant flowing out of the diffuser portion 162 c of the ejector16 flows into the discharge side evaporator 17. In the discharge sideevaporator 17, the low-pressure refrigerant flowing therein isevaporated by absorbing heat from air blown by the blower fan 17 a.Therefore, air blown by the blower fan 17 a can be cooled by thedischarge side evaporator 17. The gas refrigerant flowing out of thedischarge side evaporator 17 is drawn into the compressor 11, and iscompressed again.

The refrigerant flowing into the suction side pipe 15 b is decompressedand expanded by the throttle mechanism 18 to become a low-pressurerefrigerant, and the low-pressure refrigerant flows into the suctionside evaporator 19. In the suction side evaporator 19, the low-pressurerefrigerant flowing therein is evaporated by absorbing heat from airblown by the blower fan 17 a and having passed through the dischargeside evaporator 17.

Therefore, air blown by the blower fan 17 a is further cooled by thedischarge side evaporator 19, and then is blown into the vehiclecompartment. The gas refrigerant flowing out of the suction sideevaporator 19 is drawn into the ejector 16 from the refrigerant suctionport 162 a, as described above.

In the ejector-type refrigerant cycle device 10 of the presentembodiment, the refrigerant flowing out of the diffuser portion 162 c ofthe ejector 16 is supplied to the discharge side evaporator 17, and therefrigerant flowing into the suction side pipe 15 b is supplied to thesuction side evaporator 19 via the throttle mechanism 18. Thus, coolingaction can be obtained in both the discharge side evaporator 17 and thesuction side evaporator 19, at the same time.

The air blown by the blower fan 17 a flows as in the arrow 100. Thus,the air blown by the blower fan 17 a passes through the discharge sideevaporator 17 and the suction side evaporator 19 in this order, and thenflows into the same space to be cooled. By the pressurizing action ofthe diffuser portion 162 c, the refrigerant evaporation temperature ofthe suction side evaporator 19 can be made lower than that of therefrigerant evaporation temperature of the discharge side evaporator 17.Thus, a temperature difference between the blown air and the refrigerantevaporation temperature can be secured in both the discharge sideevaporator 17 and the suction side evaporator 19, thereby effectivelycooling the blown air.

Because the downstream side of the discharge side evaporator 17 isconnected to the refrigerant suction side of the compressor 11, therefrigerant pressurized in the diffuser portion 162 c can be drawn intothe compressor 11. Therefore, the suction pressure of the refrigerant ofthe compressor 11 can be increased, and the drive power of thecompressor 11 can be reduced. Thus, the COP can be effectively improvedin the entire cycle of the ejector-type refrigerant cycle device 10.

Furthermore, in the present embodiment, since the above-mentionedejector 16 is adopted, ejector efficiency be can be improved, andthereby the COP can be improved effectively. That is, in the ejector 16of the present embodiment, the taper portion 161 c defining therefrigerant passage of the nozzle 161 is divided into the first andsecond taper portions 161 e, 161 f.

Furthermore, the increase decree of the refrigerant passage sectionalarea in the second taper portion 161 f is made larger than the increasedegree of the refrigerant passage sectional area in the first taperportion 161 e, such that the first expanding angle θ1 at the outlet sideof the first taper portion 161 e on the standard cross section and thesecond expanding angle θ2 at the outlet side of the second taper portion161 f on the standard cross section are made to satisfy the relationshipof the formula F3.

Thus, even when gas-liquid two-phase refrigerant flowing into the nozzle161 is decompressed and expanded while passing through the first taperportion 161 e and the second taper portion 161 f in this order, therefrigerant passage area of the nozzle 161 can be enlarged to correspondto the volume expansion, even when the fluid volume is expanded by theincrease of the gas ratio.

In this case, it is possible to effectively reduce the loss due to thepassage resistance when the refrigerant passes through the first taperportion 161 e and the second taper portion 161 f in this order. Thus,the decompression stage of the refrigerant in the nozzle 161 can beapproached to the isoentropic curved line, thereby improving the nozzleefficiency ηnoz.

Furthermore, the end expanding angle θ3 at the outlet side of the endtaper portion 161 d on the standard cross section and the secondexpanding angle θ2 are set to satisfy the relationship of the formulaF4, thereby restricting the jet refrigerant jetted from the refrigerantjet port 161 a from being unnecessary expanded in a radial directionthat is perpendicular to the axial line φ.

The suction refrigerant drawn into the ejector 16 from the refrigerantsuction port 162 a easily flows into the inside of the ejector 16, andthereby it can restrict the flow amount Ge of the suction refrigerant isnot reduced. As a result, even when the refrigerant with a gas-liquidtwo-phase state flows into the nozzle 161, it can prevent the nozzleefficiency ηnoz and the ejector efficiency ηe from being reduced,thereby effectively improving the COP.

Furthermore, in the ejector 16 of the present embodiment, the secondtaper portion 161 f is formed into a curved line with a slight convex atthe inside side of the refrigerant passage on the standard crosssection. Thus, even when the increase degree of the refrigerant passagesectional area of the second taper portion 161 f is smoothly changed,the decompression stage of the refrigerant in the nozzle 161 can befurther approached to the decompression stage of the isoentropic curvedline. Therefore, it can effectively prevent a decrease of the nozzleefficiency ηnoz.

In the present embodiment, the second taper portion 161 f may be formedinto a straight line shape on the standard cross section. Even in thiscase, the second taper portion 161 f can be easily produced to reducethe product cost, while the decompression stage of the refrigerant inthe nozzle 161 can be approached to the decompression stage of theisoentropic curved line to prevent a decrease of the nozzle efficiencyηnoz.

Furthermore, in the present embodiment, because the second expandingangle θ2 is made equal to or larger than 1.33 times of the firstexpanding angle θ1 (i.e., θ2/θ1≧1.33), the nozzle efficiency ηnoz can bestably improved. The detail will be described with reference to FIG. 4.FIG. 4 is a graph showing the relationship between the second expandingangle θ2 and the nozzle efficiency ηnoz.

More specifically, in FIG. 4, the relationships between the secondexpanding angle θ2 and the nozzle efficiency ηnoz are estimated, whengas-liquid refrigerant having a predetermined different pressures flowsinto the nozzle 161 in a case where the nozzle 161 with the firstexpanding angle θ1 of 0.75 degree (°) is used. Furthermore, thedischarge side refrigerant pressure of the nozzle 161 is changed to in arange of 0.248 MPa-0.428 MPa.

As shown in FIG. 4, when the second expanding angle θ2 is in a range of0.5° to 1°, the nozzle efficiency is approximately equal regardless ofthe refrigerant pressure at the refrigerant outlet side of the nozzle161. However, when the second expanding angle θ2 is equal to or largerthan 1 (i.e., θ2/θ1≧1.33), the nozzle efficiency can be increased.

As a result, in the present embodiment, even when the refrigerant with agas-liquid two-phase state flows into the nozzle 161, it can prevent thenozzle efficiency ηnoz and the ejector efficiency ηe in the entire cyclefrom being reduced. Furthermore, in the present embodiment, since theabove-mentioned ejector 16 is used for the ejector-type refrigerantcycle device 10, the COP can be improved effectively in the ejector-typerefrigerant cycle device 10.

(Second Embodiment)

A second embodiment of the present invention will be described withreference to FIG. 5. In the present embodiment, as shown in FIG. 5, anintroduction taper portion 161 g is provided additionally with respectto the nozzle 161 of the above-described first embodiment. Theintroduction taper portion 161 g is provided in the inner peripheralsurface defining the refrigerant passage of the nozzle 161 in a rangefrom the throat portion 161 b to the first taper portion 161 e in therefrigerant flow direction, such that the refrigerant passage sectionalarea is gradually increased as toward the refrigerant flow direction.

FIG. 5 is an enlarged sectional view of the nozzle 161 of the presentembodiment, and is a drawing corresponding to FIG. 3 of theabove-described first embodiment. In FIG. 5, parts similar to orcorresponding to those of the first embodiment are indicated by the samereference numbers. This is the same also in the following drawings.

The introduction taper portion 161 g is formed to satisfy the followingformula F5, when an expanding angle at the outlet side of theintroduction taper portion 161 g on the standard cross section is θin.θin>θ1  (F5)

That is, the introduction expanding angle θin is made larger than thefirst expanding angle θ1. Thus, the increase degree of the refrigerantpassage sectional area in the introduction taper portion 161 g is largerthan the increase degree of the refrigerant passage sectional area inthe first taper portion 161 e.

Furthermore, in the present embodiment, the introduction taper portion161 g is formed into a curved line with a slight convex at the radialouter side of the refrigerant passage of the nozzle 161 on the standardcross section. The introduction taper portion 161 g and the first taperportion 161 e are smoothly connected at a connection portion byround-chamfering, similarly to the other connection portion of the firstembodiment.

Other configurations and operation of the present embodiment are similarto those of the above-described first embodiment. Thus, in the presentembodiment, even when the refrigerant with a gas-liquid two-phase stateflows into the nozzle 161 of the ejector 16, it can prevent the nozzleefficiency ηnoz and the ejector efficiency ηe in the entire ejector 16from being reduced, similarly to the above-described first embodiment.

Furthermore, in the present embodiment, the introduction expanding angleθin and the first expanding angle θ1 are set to satisfy the relationshipof the formula F5, thereby further effectively improving the nozzleefficiency ηnoz.

When gas-liquid two-phase refrigerant flowing into the nozzle 161 isdecompressed and expanded while passing through the throat portion 161b, the introduction taper portion 161 g, the first taper portion 161 eand the second taper portion 161 f in this order, the gas ratio israpidly increased at a position immediately after passing through thethroat portion 161 b in the nozzle 161.

In the present embodiment, because the introduction taper portion 161 gis provided such that the introduction expanding angle θin is madelarger than the first expanding angle θ1, the refrigerant passagesectional area can be enlarged to correspond to the rapid volumeexpansion due to a rapid increase of the gas ratio, thereby furthereffectively improving the nozzle efficiency ηnoz.

Furthermore, in the ejector 16 of the present embodiment, theintroduction taper portion 161 g is formed into a curved line with aslight convex on the radial outer side of the refrigerant passage on thestandard cross section. Thus, the increase degree of the refrigerantpassage sectional area of the introduction taper portion 161 g issmoothly changed, and thereby the decompression stage of the refrigerantin the nozzle 161 can be more approached to the decompression stage ofthe isoentropic curved line. Therefore, it can further prevent adecrease of the nozzle efficiency ηnoz.

In the present embodiment, the introduction taper portion 161 g may beformed into a straight line shape on the standard cross section. In thiscase, the introduction taper portion 161 g can be easily produced toreduce the product cost, while the decompression stage of therefrigerant in the nozzle 161 can be approached to the decompressionstage of the isoentropic curved line to prevent a decrease of the nozzleefficiency ηnoz.

(Third Embodiment)

In the present embodiment, as shown in FIG. 6, a needle 163 is arrangedin the refrigerant passage of the nozzle 161, with respect to theabove-described first embodiment.

The needle 163 is arranged in the refrigerant passage of the nozzle 161to extend coaxially with the axial line φ, and is formed into a needleshape in which the sectional area perpendicular to the axial directionis gradually reduced as toward the refrigerant flow direction. Thus, inthe nozzle 161 of the present embodiment, a refrigerant passage having acircular-ring shape in cross-section (e.g., a doughnut-like shape) isformed between the outer peripheral surface of the needle 163 and theinner peripheral surface of the nozzle 161 that is configured similarlyto the above described first embodiment.

Furthermore, on the standard cross section of the nozzle 161, the outerperipheral surface of the needle 163 is formed into a straight line in arange positioned radial inside of the taper portion 161 c of the nozzle161. In the nozzle 161 of the present embodiment, the taper portion 161c is divided into first and second taper portions 161 e, 161 f,similarly to the first embodiment. Thus, even in the present embodiment,the first expanding angle θ1 and the second expanding angle θ2 satisfythe above formula F3, such that the second expanding angle θ2 is largerthan the first expanding angle θ1.

The refrigerant passage, formed between the outer peripheral surface ofthe needle 163 and the inner peripheral surface of the nozzle 161,includes a first expanding passage portion 164 a and a second expandingpassage portion 164 b arranged downstream of the first expanding passageportion 164 a. In the first expanding passage portion 164 a, therefrigerant passage sectional area is gradually enlarged toward therefrigerant flow direction in the range corresponding to the first taperportion 161 e. Furthermore, in the second expanding passage portion 164b, the refrigerant passage sectional area is gradually enlarged towardthe refrigerant flow direction in the range corresponding to the secondtaper portion 161 f.

Thus, the increase degree of the refrigerant passage sectional area inthe second expanding passage portion 164 b is larger than the increasedegree of the refrigerant passage sectional area in the first expandingpassage portion 164 a. Accordingly, in the present embodiment, therefrigerant passage sectional area of the circular-ring shapedrefrigerant passage of the nozzle 161 is changed in a range from thethroat portion 161 b to the refrigerant jet port 161 a, similarly to thechange in the refrigerant passage sectional area of the nozzle 161 ofthe above-described first embodiment.

Other configurations and operation of the present embodiment are similarto those of the above-described first embodiment. Thus, in the ejectorof the present embodiment, even when the refrigerant with a gas-liquidtwo-phase state flows into the nozzle 161 of the ejector 16, it canprevent the nozzle efficiency ηnoz and the ejector efficiency ηe in theentire ejector 16 from being reduced, similarly to the above-describedfirst embodiment.

The needle 163 having a cross section area, which is gradually reducedas toward downstream, is disposed in the end taper portion 161 d, sothat an increase degree of the refrigerant passage sectional areadefined in the end taper portion 161 d of the nozzle 160 can be moreincreased as compared with a case where the needle 163 is not disposed.

As a result, it can prevent the refrigerant jetted from the refrigerantinjection port 161 a from being unnecessary expanded in a nozzle radialdirection that is perpendicular to the axial line φ, and the energy losscaused in the taper portion 161 d can be reduced, thereby furtherrestricting a decrease of the nozzle efficiency ηnoz.

(Fourth Embodiment)

In a fourth embodiment, similarly to the above-described thirdembodiment, a needle 163 is arranged in the refrigerant passage of thenozzle 161, with respect to the above-described second embodiment, asshown in FIG. 7. Accordingly, in the present embodiment, the refrigerantpassage sectional area of the circular-ring shaped refrigerant passageof the nozzle 161 in cross section is changed in a range from the throatportion 161 b to the refrigerant jet port 161 a via the introductiontaper portion 161 g, similarly to the change in the refrigerant passagesectional area of the nozzle 161 of the above-described secondembodiment.

Other configurations and operation of the present embodiment are similarto those of the above-described second embodiment. Thus, in the ejector16 of the present embodiment, the effects similar to the secondembodiment can be obtained. In addition, similarly to theabove-described third embodiment, it can restrict the refrigerant jettedfrom the refrigerant injection port 161 a from being unnecessaryexpanded in a nozzle radial direction that is perpendicular to the axialline φ, and the energy loss caused in the end taper portion 161 d can bereduced, thereby further restricting a decrease in the nozzle efficiencyηnoz.

(Fifth Embodiment)

In the above-described third and fourth embodiments, in order to makethe change of the refrigerant passage sectional area of the circularring shape in cross section between the outer peripheral surface of theneedle 163 and the inner peripheral surface of the nozzle 161 to besimilar to the change of the refrigerant passage sectional area of thenozzle 161 in the first and second embodiments, the taper portion 161 cis divided into the first and second taper portions 161 e, 161 f. Incontrast, in a fifth embodiment, the shape of a needle 163 used in thepresent embodiment is changed without dividing the taper portion 160 cinto two parts.

Specifically, the needle 163 of the present embodiment is divided intothree reduction parts of an introduction reduction portion 163 a, afirst reduction portion 163 b and a second reduction portion 163 c.Furthermore, on the standard cross section, a reduction degree of thesectional area of the introduction reduction portion 163 a is madelarger than a reduction degree of the sectional area of the firstreduction portion 163 b, and a reduction degree of the sectional area ofthe second reduction portion 163 c is made larger than a reductiondegree of the sectional area of the first reduction portion 163 b.

In the present embodiment, all the taper portion 161 c of the nozzle 161is formed into a straight line shape on the standard cross section.Thus, in the present, embodiment, the taper portion 161 c is not dividedinto the first and second taper portions 161 e, 161 f.

Accordingly, in the present embodiment, the refrigerant passagesectional area of the circular-ring shaped refrigerant passage of thenozzle 161 is changed in a range from the throat portion 161 b to therefrigerant jet port 161 a, similarly to the change in the refrigerantpassage sectional area of the nozzle 161 of the above-described secondembodiment. Other configurations and operation of the present embodimentare similar to those of the above-described second embodiment.

Thus, in the ejector 16 of the present embodiment, the same effects asin the fourth embodiment can be obtained. In the fifth embodiment shownin FIG. 8, the introduction reduction portion 163 a may be not providedin the needle 163, and an introduction taper portion 161 g shown in FIG.7 may be provided in the nozzle 161. Even in this case, the same effectcan be obtained. In the present embodiment shown in FIG. 8, the taperportion 161 c of the nozzle 161 for defining the refrigerant passagetogether with the needle 163 is formed into a straight line shape on thestandard cross section, and thereby the taper portion 161 c can beeasily formed.

In the present embodiment, the introduction reduction portion 163 a maybe omitted from the needle 163. In this case, the refrigerant passagesectional area of the circular-ring shaped refrigerant passage of thenozzle 161 in cross section is changed in a range from the throatportion 161 b to the refrigerant jet port 161 a, similarly to the changein the refrigerant passage sectional area of the nozzle 161 of theabove-described first embodiment. Therefore, the same effects as in thethird embodiment can be obtained.

(Sixth Embodiment)

In the present embodiment, in order to make the change of therefrigerant passage sectional area of the circular ring shape in crosssection between the outer peripheral surface of the needle 163 and theinner peripheral surface of the nozzle 161 to be similar to the changeof the refrigerant passage sectional area of the nozzle 161 in theabove-described first or second embodiment, the taper portion 161 c isdivided into the first and second taper portions 161 e, 161 f, and atthe same time, the shape of a needle 163 used in the present embodimentis also changed.

More specifically, in the present embodiment, the nozzle 161 providedwith the first and second taper portions 161 e, 161 f and the end taperportion 161 d similarly to the nozzle 161 of the above-described firstembodiment, and the needle 163 provided with an introduction reductionportion 163 a, first and second reduction portions 163 b, 163 c arecombined thereby changing the refrigerant passage sectional area. Theneedle 163 is provided with the first and second reduction portions 163b, 163 c, but the reduction degrees of the first and second reductionportions 163 b, 163 c are different from those of the above-describedfifth embodiment.

Other configurations and operation of the present embodiment are similarto those of the above-described second embodiment. Thus, in the ejector16 of the present embodiment, the same effects as in the fourthembodiment can be obtained. In the sixth embodiment shown in FIG. 9, theintroduction reduction portion 163 a may be not provided in the needle163, and an introduction taper portion 161 g may be provided on theinner peripheral surface of the nozzle 161. Even in this case, the sameeffect can be obtained.

In the present embodiment, the nozzle 161 is provided with the first andsecond taper portions 161 e, 161 f and the end taper portion 161 d,although the extending angles of the first and second taper portions 161e, 161 f and the end taper portion 161 d are different from that of theabove-described first embodiment. Thus, the refrigerant passagesectional area of the circular-ring shaped refrigerant passage of thenozzle 161 in cross section can be changed, similarly to the change inthe refrigerant passage sectional area of the nozzle 161 of theabove-described first embodiment. Therefore, the same effects as in thethird embodiment can be obtained.

By suitably combining the shapes of the outer peripheral surface of theneedle 163 and the inner peripheral surface of the nozzle 161, therefrigerant passage sectional area of the circular-ring shapedrefrigerant passage between the outer peripheral surface of the needle163 and the inner peripheral surface of the nozzle 161 can be changedsimilarly to the change in the refrigerant passage sectional area of thenozzle 161 of the above-described first or second embodiment.

(Other Embodiment)

The present invention is not limited to the above-described embodiments,and the following various modifications are possible within the samescope as the invention.

(1) In the above-described embodiments, the ejector 16 is used for anejector-type refrigerant cycle device 10 in which the refrigerant flowis branched in the branch portion 14 located upstream of the nozzle 161.However, the present invention is not limited to it. For example, in theejector-type refrigerant cycle device 10 shown in FIG. 1, the expansionvalve 13 may be located in the nozzle side pipe 15 a extending from thebranch portion 14 to the refrigerant inlet side of the nozzle 161 of theejector 16.

For example, the ejector 16 of the present invention may be applied toan ejector-type refrigerant cycle device 10 shown in FIG. 10, in whichthe receiver 12 b, the expansion valve 13, the branch portion 14 and thesuction side pipe 15 b are omitted as compared with the ejector-typerefrigerant cycle device 10 shown in FIG. 1. In contrast, in theejector-type refrigerant cycle device 10 shown in FIG. 10, alow-pressure gas-liquid separator (e.g., accumulator) 20 is arrangeddownstream of the diffuser portion 162 c of the ejector 16, such thatthe liquid refrigerant separated in the accumulator 20 flows into thesuction side evaporator 19. In the ejector-type refrigerant cycle device10, the discharge side evaporator 17 may be omitted.

The ejector 16 may be applied to an ejector-type refrigerant cycledevice 10 shown in FIG. 11, in which the discharge side evaporator 17 isomitted, the expansion valve 13 is located in the nozzle side pipe 15 a,and an inner heat exchanger 21 is provided, with respect to theejector-type refrigerant cycle device 10 shown in FIG. 1. The inner heatexchanger 21 is provided to perform heat exchange between a low-pressurerefrigerant flowing out of the ejector 16 and a high-pressurerefrigerant flowing from the branch portion 14, into the suction sidepipe 15 b. In this case, the enthalpy of the refrigerant flowing intothe suction side evaporator 19 can be decreased, and the refrigeratingcapacity obtained in the suction side evaporator 19 can be increased.

Alternatively, the ejector 16 may be applied to an ejector-typerefrigerant cycle device 10 shown in FIG. 12, in which the branchportion 14 is disposed at a refrigerant outlet side of the ejector 16,such that one refrigerant branched in the branch portion 14 is suppliedto the discharge side evaporator 17 and other one refrigerant branchedin the branch portion 14 flows into the suction side evaporator 19.

(2) In the above-described embodiments, a flon-based refrigerant is usedas the refrigerant for a refrigerant cycle. However, the kind of therefrigerant is not limited to it. For example, hydrocarbon-basedrefrigerant, carbon dioxide, etc. may be used. Furthermore, the ejector16 of the present invention may be applied to a super-criticalrefrigerant cycle in which a refrigerant pressure on the high-pressureside exceeds the critical pressure of the refrigerant.

(3) In the above-described embodiments, the ejector 16 of the presentinvention is used for an ejector-type refrigerant cycle device 10 for avehicle air conditioner (i.e., a refrigeration cycle device for avehicle). However, the present invention is not limited to it. Theejector of the present invention may be applied to an ejector-typerefrigerant cycle device of a fixed type, such as a business-userefrigerating/cooling device, a cooling device for vending machines, ashowcase with a refrigeration function, etc., in addition to therefrigeration cycle device for a vehicle.

(4) In the above-described embodiments, the discharge side evaporator 17and the suction side evaporator 19 are integrally assembled to beintegrated. As an integrated structure, components of both theevaporators 17, 19 may be made of aluminum, and may be bonded integrallyby using bonding means such as brazing. Alternatively, the components ofboth the evaporators 17, 19 may be connected integrally by using amechanical engagement means such as a bolt-fastening, while a spaceabout 10 mm or less is provided between the discharge side evaporator 17and the suction side evaporator 19.

A heat exchanger of a fin and tube type may be used as the dischargeside evaporator 17 and the suction side evaporator 19. In this case,fins may be used in common in both the discharge side evaporator 17 andthe suction side evaporator 19, and refrigerant passages of tubescontacting the fins may be configured to be separated from each other inboth the evaporators 17 and 19.

(5) In the above-described embodiments, the discharge side evaporator 17and the suction side evaporator 19 are adapted as an interior heatexchanger, and the radiator 12 is adapted as an exterior heat exchangerfor radiating heat to the atmosphere. However, an ejector of the presentinvention may be applied to a heat pump cycle, in which the dischargeside evaporator 17 and the suction side evaporator 19 are configured asthe exterior heat exchanger to absorb heat from a heat source such asthe atmosphere, and the radiator 12 may be configured as the interiorheat exchanger for heating the refrigerant that is used to heat air orwater to be heated.

The technical features of the above-described embodiments may besuitably combined if there are no contradiction therebetween.

1. An ejector comprising: a nozzle configured to decompress and expand afluid and to jet the fluid from a fluid jet port; and a body providedwith a fluid suction port from which a fluid is drawn by a high-speedjet fluid jetted from the fluid jet port, and a pressure increasingportion in which a velocity energy of a mixture fluid between the jetfluid and a suction fluid drawn from the fluid suction port is convertedto a pressure energy thereof, wherein an inner peripheral surface of thenozzle defining a fluid passage includes a throat portion in which afluid passage sectional area of the fluid passage is most reduced, afirst taper portion arranged downstream of the throat portion togradually enlarge the fluid passage sectional area as toward a flowdirection of the jet fluid, a second taper portion arranged downstreamof the first taper portion to gradually enlarge the fluid passagesectional area as toward the flow direction of the jet fluid, and an endtaper portion arranged in a range from an outlet side of the secondtaper portion to the fluid jet port, to gradually enlarge the fluidpassage sectional area as toward the flow direction of the jet fluid,when an axial cross section including an axial line of the nozzle isdefined as a standard cross section, a second expanding angle at anoutlet side of the second taper portion on the standard cross section islarger than a first expanding angle at an outlet side of the first taperportion on the standard cross section, and an end expanding angle at anoutlet side of the end taper portion on the standard cross section issmaller than the second expanding angle.
 2. The ejector according toclaim 1, wherein the second taper portion is formed into a curved lineshape with a convex at the fluid passage side, on the standard crosssection.
 3. The ejector according to claim 1, wherein the second taperportion is formed into a straight line shape on the standard crosssection.
 4. The ejector according to claim 1, wherein the innerperipheral surface of the nozzle defining the fluid passage furtherincludes an introduction taper portion arranged in a range from thethroat portion to the first taper portion, to gradually enlarge thefluid passage sectional area as toward the flow direction of the jetfluid, and an introduction expanding angle at an outlet side of theintroduction taper portion on the standard cross section is larger thanthe first expanding angle.
 5. The ejector according to claim 4, whereinthe introduction taper portion is formed into a curved line shape with aconvex at a radial outside of the nozzle, on the standard cross section.6. The ejector according to claim 4, wherein the introduction taperportion is formed into a straight line shape on the standard crosssection.
 7. The ejector according to claim 1, wherein a ratio of thesecond expanding angle to the first expanding angle is equal to orlarger than 1.33.